1. Field of the Invention
The present invention relates to a method of removing, collecting, and treating floating substances such as oil flowing out to the sea, lakes and marshes, rivers, waterways, and the like as well as a red tide caused by the abnormal increase of plankton in the sea and fresh water and an apparatus for removing, collecting, and treating the floating substances.
2. Description of the Related Art
Conventionally, waste water, which is discharged from kitchens, meat and marine product processing factories, oil manufacturing factories, oil and fat processing factories, repair shops, gas stations, and the like, includes a lot of animal-oil-, vegetable-oil-, and mineral-oil-containing wastes, and animal and vegetable oily materials which are made when various materials are processed.
There have been employed a method of surrounding flowing-out oil and red tide plankton which float on the large water surface of the sea and lakes and extend to a large area by an oil fence and the like and scooping them by a pump or a combined harvester or a method of condensing and settling them after they are diffused by chemical agents.
Although methods similar to the above methods are employed as countermeasures against a red tide, chemical agents for killing plankton are also used, in addition to the above methods. Further, in the Inland Sea of Japan, Lake Biwa and Lake Suwa, the quality of entering water is regulated so that the nitrogen and phosphorus contained in the water is lowered to prevent the overnourishment of the water as a drastic countermeasure for the occurrence of a red tide.
When flowing-out oil and red tide plankton floating on the large water surface of the sea or lakes are collected by a collection ship using the pump or the like, a large amount of water is pumped up at the same time as well as the amount of the collected oil and plankton is only a few percents of the water.
Therefore, since a storage rank of a large capacity, a centrifugal separator, a filtering device and the like must be equipped on the collection ship, there is a problem that the size of the above devices is increased and the cost thereof is increased as well as it is difficult to moor the collection ship at a proper location.
The flowing-out oil on the sea surface is made to aggregates when it is made less fluid in winter, whereas when the red tide plankton increases, dead plankton is also made to aggregates and these aggregates deposit on the bottom of the sea and lakes as a layer. Thus, it is difficult to pump up the aggregates from the bottom.
Although the combined harvester is effective to collect aggregated floating substances, it cannot be used to floating substances having high fluidity. Although there is a method of using the combined harvester in combination with the pump, there is a problem that the apparatus is increased in size and cost. Further, there is also a problem that since the apparatus is not used ordinarily and used only in an emergency, it is difficult to prepare them in a large number as well as when the size of the apparatus is increased, there arises a problem that the collecting ship cannot perform a collection job in a narrow area such as a location near to the seashore.
When the chemical agents are sprayed, it cleans the water surface only temporarily and oil and plankton are diffused in a large area or deposited on the bottom of the sea and lakes and accordingly water becomes polluted in a larger area and adversely affected for a long time. Therefore, there arises a problem that the ecological system of the sea and lakes are seriously affected by the spray of chemical agents.
Next, when the chemical agents are sprayed to kill plankton as a countermeasure against a red tide, the ecological system is seriously affected by them, although the increase of the red tide can be suppressed. Thus, copper sulfate which was used initially is not used now because the toxicity thereof is too high. At present, any chemical agents which are effective without affecting the ecological system have not yet been developed.